From 8a56be66601e5f21f15a76bfc932c9beb8f7cdee Mon Sep 17 00:00:00 2001
From: Duncan Lowther <Duncan.Lowther@glasgow.ac.uk>
Date: Tue, 7 Apr 2026 16:41:40 +0100
Subject: [PATCH] extmod/moductypes: Be more defensive with
 uctypes_struct_agg_size args.

Eliminates read-beyond-end when calling `uctypes_struct_agg_size()` on the
length 1 tuple (uctypes.ARRAY ,).

Signed-off-by: Duncan Lowther <Duncan.Lowther@glasgow.ac.uk>
---
 extmod/moductypes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/extmod/moductypes.c b/extmod/moductypes.c
index ed865f4263..7cac41dbcf 100644
--- a/extmod/moductypes.c
+++ b/extmod/moductypes.c
@@ -155,7 +155,7 @@ static inline mp_uint_t uctypes_struct_scalar_size(int val_type) {
 
 // Get size of aggregate type descriptor
 static mp_uint_t uctypes_struct_agg_size(mp_obj_tuple_t *t, int layout_type, mp_uint_t *max_field_size) {
-    if (t->len == 0) {
+    if (t->len < 2) {
         syntax_error();
     }